OTFS分数多普勒信道估计与检测论文整理3(摘要)

写在前面:该文写于2023.7.27,整理了IEEE上最新OTFS方面(大多为2023年发表)顶刊论文,主要涉及到分数多普勒问题(一共44篇,每次更新5篇)。写文的初衷是为了理解分数多普勒的问题背景,并了解现有针对分数多普勒问题的一些成熟解决方案,因此在时间有限的前提下只针对摘要核心部分(问题背景、解决方法、简要细节)做出翻译,并对摘要中核心的部分进行标红或划线处理,同时对英文摘要进行拆分,方便大家快速找到所需要的内容,摘要最后写了总结,大多为摘要概括以及本人的一些简单想法或疑问。

OTFS考虑分数多普勒信道估计与检测相关论文整理3(摘要)

  • 一、论文11:A Novel OTFS System Based on DFrFT-OFDM
  • 二、论文12:Channel Estimation and Equalization for CP-OFDM-based OTFS in Fractional Doppler Channels
  • 三、论文13:Deterministic Pilot Design and Channel Estimation for Downlink Massive MIMO-OTFS Systems in Presence of the Fractional Doppler
  • 四、论文14:Embedded Delay-Doppler Channel Estimation for Orthogonal Time Frequency Space Modulation
  • 五、论文15:Low-Complexity Channel Matrix Calculation for OTFS Systems with Fractional Delay and Doppler


一、论文11:A Novel OTFS System Based on DFrFT-OFDM

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A Novel OTFS System Based on DFrFT-OFDM
Mallaiah, Renikunta and Mani, V. V.  2022 June
IEEE Wireless Communications Letters

原文:
  背景:Orthogonal Time Frequency Space modulation (OTFS) is a promising modulation technique expected to counter the severe Doppler effects encountered in a doubly dispersive channel. OTFS scheme is developed on the basis of Orthogonal Frequency Division Multiplexing (OFDM) systems to support communication between high-speed vehicles, whose superiority lies in the domain of the equivalent channel. OTFS converts the Time-Frequency (TF) domain channel in the OFDM system to Delay-Doppler (DD) domain channel that becomes a handy tool to overcome the difficulties faced in a frequency selective channel. 本文方法:This letter presents an OTFS system design that is developed on the Discrete Fractional Fourier Transform (DFrFT) based OFDM system, which is designed to perform better compared to the conventional OTFS system with the same design complexity. The simulation results evidentially show 1 dB gain in power at a Bit-Error-Rate (BER) of and a significant 3 dB decrement in the PAPR when a high power pilot with a 25 dB is inserted in the OTFS data frame.

翻译:

一种基于DFrFT-OFDM新的OTFS系统
背景:正交时频空间调制(OTFS)是一种很有前景的调制技术,有望对抗双色散信道中遇到的严重多普勒效应。OTFS方案是在正交频分复用(OFDM)系统的基础上发展起来的,用于支持高速车辆之间的通信,其优越性在于等效信道域。OTFS将OFDM系统中的时频(TF)域信道转换为延迟多普勒(DD)域信道,成为克服频率选择性信道中面临的困难的便捷工具。本文方法:该论文介绍了一种在基于离散分数傅里叶变换(DFrFT) 的OFDM系统上开发的OTFS系统设计,与具有相同设计复杂度的传统OTFS系统相比,该系统的性能更好。仿真结果明显表明,当25dB的高功率导频插入OTFS数据帧时,误码率(BER)为 时的功率增益为1dB,PAPR显着下降3dB。

总结:论文在OTFS系统设计的基础上引入了离散分数傅里叶变换(DFrFT),不会提高复杂度的同时,在降低PAPR方面具有优势。

二、论文12:Channel Estimation and Equalization for CP-OFDM-based OTFS in Fractional Doppler Channels

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Channel Estimation and Equalization for CP-OFDM-based OTFS in Fractional Doppler Channels
Hashimoto, Noriyuki and Osawa, Noboru and Yamazaki, Kosuke and Ibi, Shinsuke
2021 June
2021 IEEE International Conference on Communications Workshops (ICC Workshops)

原文:
  背景:Orthogonal time frequency and space (OTFS) modulation is a promising technology that satisfies high-Doppler requirements for future mobile systems. OTFS encodes information symbols and pilot symbols into the two-dimensional (2D) delay-Doppler (DD) domain. The received symbols suffer from inter-Doppler interference (IDI) in fading channels with fractional Doppler shifts sampled at noninteger indices in the DD domain. The IDI has been treated as an unavoidable effect because the fractional Doppler shifts cannot be obtained directly from the received pilot symbols. 本文方法:This paper provides a solution to channel estimation for fractional Doppler channels with lower computational complexity than a conventional channel estimation method using a pseudo sequence. The proposed estimation provides new insight into the OTFS input-output relation in the DD domain as a 2D circular convolution with a small approximation. According to the input-output relation, we also provide a low-complexity channel equalization method using the estimated channel information. 性能分析:We demonstrate the error performance of the proposed channel estimation and equalization in a high-Doppler channel by simulations. The simulation results show that the proposed channel estimation method outperforms the conventional channel estimation. The results also show that the proposed equalization method has a similar performance to the minimum mean square error equalizer using matrix inversion.

翻译:

分数多普勒信道下基于CP-OFDM的OTFS信道估计与均衡技术
背景:正交时频和空间(OTFS)调制是一项很有前途的技术,可以满足未来移动系统的高多普勒要求。 OTFS 将信息符号和导频符号编码到二维 (2D) 延迟多普勒 (DD) 域中。 接收到的符号在衰落信道中遭受多普勒间干扰 (IDI),其中分数多普勒频移是在 DD 域中的非整数索引处采样的。 IDI 已被视为不可避免的影响,因为分数多普勒频移无法直接从接收到的导频符号获得。 本文方法:本文提供了一种分数多普勒信道的信道估计解决方案,与使用伪序列的传统信道估计方法相比,其计算复杂度更低。 所提出的估计为 DD 域中的 OTFS 输入输出关系提供了新的见解,作为具有小近似值的 2D 循环卷积。 根据输入输出关系,我们还提供了一种使用估计信道信息的低复杂度信道均衡方法。 性能分析:我们通过仿真演示了高多普勒信道中所提出的信道估计和均衡的误差性能。 仿真结果表明,所提出的信道估计方法优于传统的信道估计。 结果还表明,所提出的均衡方法与使用矩阵求逆的最小均方误差均衡器具有相似的性能。

总结:该论文针对分数多普勒影响产生的IDI,难以通过接收到的导频信号直接去除这一问题;对于OTFS输入输出关系方面做出近似,提出了一个针对分数多普勒信道的低计算复杂度的信道估计方法。

三、论文13:Deterministic Pilot Design and Channel Estimation for Downlink Massive MIMO-OTFS Systems in Presence of the Fractional Doppler

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Deterministic Pilot Design and Channel Estimation for Downlink Massive MIMO-OTFS Systems in Presence of the Fractional Doppler
Shi, Ding and Wang, Wenjin and You, Li and Song, Xiaohang and Hong, Yi and Gao, Xiqi and Fettweis, Gerhard
2021 Nov
IEEE Transactions on Wireless Communications

原文:
  背景(OTFS与MIMO结合的意义与不足):Although the combination of the orthogonal time frequency space (OTFS) modulation and the massive multiple-input multiple-output (MIMO) technology can make communication systems perform better in high-mobility scenarios, there are still many challenges in downlink channel estimation owing to inaccurate modeling and high pilot overhead in practical systems. 本文方法:In this paper, we propose a channel state information (CSI) acquisition scheme for downlink massive MIMO-OTFS in presence of the fractional Doppler, including deterministic pilot design and channel estimation algorithm. 算法细节(四点):First, we analyze the input-output relationship of the single-input single-output (SISO) OTFS based on the orthogonal frequency division multiplexing (OFDM) modem and extend it to massive MIMO-OTFS. |Moreover, we formulate an accurate model for the practical system in which the fractional Doppler is considered and the influence of subpaths is revealed. A deterministic pilot design is then proposed based on the model and the structure of the pilot matrix to reduce pilot overhead and save memory consumption. Since channel geometry changes very slowly relative to the communication timescale, we put forward a modified sensing matrix based channel estimation (MSMCE) algorithm to acquire the downlink CSI. 性能分析:Simulation results demonstrate that the proposed downlink CSI acquisition scheme has significant advantages over traditional algorithms.

翻译:

分数多普勒下MIMO-OTFS系统下行链路确定导频设计与信道估计
背景(OTFS与MIMO结合的意义与不足):虽然正交时频空间(OTFS)调制与大规模多输入多输出(MIMO)技术的结合可以使通信系统在高移动场景下表现更好,但由于实际系统中建模不准确和导频开销较高,下行信道估计仍然存在许多挑战。 本文方法:在本文中,我们提出了一种存在分数多普勒的下行链路大规模MIMO-OTFS的信道状态信息(CSI)获取方案,包括确定性导频设计和信道估计算法。 算法细节(四点):首先,我们分析了基于正交频分复用(OFDM)调制解调器的单输入单输出(SISO)OTFS的输入输出关系,并将其扩展到大规模MIMO-OTFS。 |此外,我们为实际系统制定了一个精确的模型,其中考虑了分数多普勒并揭示了子路径的影响。 然后根据模型和导频矩阵的结构提出确定性导频设计,以减少导频开销并节省内存消耗。 由于信道几何形状相对于通信时间尺度变化非常缓慢,因此我们提出了一种改进的基于感知矩阵的信道估计(MSMCE)算法来获取下行链路CSI。 性能分析:仿真结果表明,所提出的下行CSI获取方案比传统算法具有显着优势。

总结:论文针对MIMO-OTFS在实际系统中可能存在的非精确建模与高导频开销等问题作出研究。该论文提出一个适用于分数多普勒下下行链路MIMO-OTFSCSI均衡方案。该方案从输入输出关系、精确建模、导频设计、感知矩阵四个方面做出改进。

四、论文14:Embedded Delay-Doppler Channel Estimation for Orthogonal Time Frequency Space Modulation

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Embedded Delay-Doppler Channel Estimation for Orthogonal Time Frequency Space Modulation
Raviteja, P. and Phan, Khoa T. and Hong, Yi and Viterbo, Emanuele
2018 Aug
2018 IEEE 88th Vehicular Technology Conference (VTC-Fall)

原文:
  背景:hogonal time frequency space (OTFS) modulation was shown to provide significant error performance advantages over orthogonal frequency division multiplexing (OFDM) over delay-Doppler channels. The channel impulse response is needed at the receiver to perform OTFS detection. 本文方法:In this work, we analyze OTFS-based channel estimation using a pilot symbol embedded in the data frame: 嵌入式导频the pilot symbol with a number of guard zero-symbols is suitably located on the delay-Doppler grid containing the information symbols. Different symbol arrangements are proposed depending on whether the channel has integer or fractional Doppler paths relative to an integer grid. The channel information is first estimated from a group of received symbols using a simple 信道估计:threshold method. The estimated information is then used for data detection within the same frame, via a message passing (MP) algorithm. 性能分析:Numerical results compare the error performance of the proposed schemes and the OTFS scheme with ideal channel estimation under similar spectral and energy efficiency. Moreover, our results show that OTFS with non-ideal channel estimation can still outperform OFDM with ideal channel estimation.

翻译:

OTFS下嵌入式时延-多普勒域信道估计
背景:事实证明,与延迟多普勒信道上的正交频分复用(OFDM)相比,正交时频空间(OTFS)调制具有显着的误码性能优势。接收器需要信道脉冲响应来执行OTFS检测。本文方法:在这项工作中,我们使用嵌入在数据帧中的导频符号来分析基于OTFS的信道估计:嵌入式导频具有多个保护零符号的导频符号适当地位于包含信息符号的延迟多普勒网格上。根据信道是否具有相对于整数网格的整数多普勒路径或分数多普勒路径,提出了不同的符号排列。首先使用简单的信道估计:threshold方法从一组接收到的符号中估计出信道信息。然后,通过消息传递(MP)算法,将估计的信息用于同一帧内的数据检测。性能分析:数值结果比较了相似频谱和能量效率下所提出方案与具有理想信道估计的OTFS方案的误差性能。此外,我们的结果表明,采用非理想信道估计的OTFS仍然优于采用理想信道估计的OFDM。

总结:这篇论文在前面的blog中精读过,提出了嵌入式导频设计,并分别推导了整数/分数多普勒下的输入输出关系。信道估计采用简单的阈值估计法,信号检测采用MP算法。

五、论文15:Low-Complexity Channel Matrix Calculation for OTFS Systems with Fractional Delay and Doppler

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Low-Complexity Channel Matrix Calculation for OTFS Systems with Fractional Delay and Doppler
Wang, Zheng and Liu, Lingjia and Yi, Yang and Calderbank, Robert and Zhang, Jianzhong
2022 Nov
MILCOM 2022 - 2022 IEEE Military Communications Conference (MILCOM)

原文:
  背景:Orthogonal Time Frequency Space (OTFS) modulation has been introduced to manage channel induced high Doppler shifts in mobile communication networks. In an OTFS system, the information carrying symbols are placed in the data frames in the delay-Doppler (DD) domain before transformed into the time domain for transmission. Accordingly, the DD domain channel matrix can be estimated using the corresponding pilots in the DD domain. For OTFS systems with integer delay and Doppler values, the underlying channel matrix in the DD domain is sparse. 问题:1.分数多普勒矩阵失去了稀疏性:However, the counterpart channel matrix is no longer sparse when the delay and Doppler values are fractional.2. 整数情况由于矩阵尺寸大仍是个耗时的问题: In fact, even for the integer case calculating the sparse channel matrix is still time-consuming due to its large size. 本文方法:To significantly reduce the computational complexity, in this paper, we introduce a low complexity algorithm for calculating the channel matrix of OTFS systems with fractional delay and Doppler. The introduced algorithm leverages the circulant property of the underlying channel matrix in the DD domain and calculates a small portion of elements in one initial block. Through some simple operation, the elements in the initial block can be replicated into other parts of the channel matrix. 性能分析:Both theoretical complexity analysis and simulation results demonstrate that our method can significantly reduce the computation complexity when computing the channel matrix. Since DD domain channel matrix is crucial for OTFS receive processing, we believe this is an important step to bring OTFS towards practical communication systems.

翻译:

分数时延/多普勒OTFS系统低复杂度信道矩阵计算
背景:正交时频空间 (OTFS) 调制已被引入来管理移动通信网络中信道引起的高多普勒频移。 在OTFS系统中,携带信息的符号被放置在延迟多普勒(DD)域的数据帧中,然后变换到时域进行传输。 因此,可以使用DD域中的对应导频来估计DD域信道矩阵。 对于具有整数延迟和多普勒值的 OTFS 系统,DD 域中的底层信道矩阵是稀疏的。 问题:然而,当时延和多普勒值为分数时,对应的信道矩阵不再稀疏。事实上,即使对于整数情况计算稀疏信道矩阵由于其尺寸很大仍然是耗时的。 本文方法:为了显着降低计算复杂度,在本文中,我们引入了一种低复杂度算法来计算具有分数延迟和多普勒的OTFS系统的信道矩阵。 引入的算法利用 DD 域中底层通道矩阵的循环特性,并计算一个初始块中的一小部分元素。 通过一些简单的操作,初始块中的元素可以复制到通道矩阵的其他部分。 性能分析:理论复杂度分析和仿真结果都表明,我们的方法可以显着降低计算信道矩阵时的计算复杂度。 由于 DD 域信道矩阵对于 OTFS 接收处理至关重要,我们相信这是将 OTFS 推向实际通信系统的重要一步。

总结:由于分数多普勒下OTFS在DD域的信道矩阵丧失了稀疏性变得复杂,同时由于矩阵尺寸较大稀疏信道矩阵的求解仍是个耗时的问题。因此,论文抓住了OTFS的循环特性,提出低复杂度(初始块不断复制得到完整矩阵)OTFS分数时延/多普勒信道矩阵计算方法。

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